[BUG] React error #418 -Claude Desktop: "Failed to load session" crash when using Figma generate_figma_design MCP tool

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Claude Desktop consistently crashes with "Failed to load session" when the Figma MCP plugin's generate_figma_design tool is called. The chat dies (app stays open) and I have to start a new conversation. This happens even in fresh sessions with minimal context.

What I've tried

Fresh conversation with minimal context
Removing the local figma-developer-mcp MCP server
Updating Claude Desktop to latest version (1.1.5749)
Different working directories
None of these resolved the issue.

Environment

Claude Desktop: v1.1.5749
macOS 26.3.1 (Apple M4 Max)
Node: v24.13.0
MCP: Figma plugin (plugin:figma:figma via mcp.figma.com)

What Should Happen?

Claude Code should open the HTML files in Chrome MCP and trigger the Figma capture script, which adds them to Figma.

Error Messages/Logs

React hydration error (19 occurrences, Mar 3–8):

[error] Uncaught Error: Minified React error #418;
visit https://react.dev/errors/418?args[]=text&args[]=

React render loop (Mar 6):

[LOCAL_SESSION] [RenderLoopDetector] RENDER LOOP in CCSessionList:
40 renders in 1000ms. React will crash with error #185
(Maximum update depth exceeded). Diagnostics: {}

Preceded by rapid re-rendering:

[LOCAL_SESSION] [RenderLoopDetector] Rapid re-rendering in SessionItem:
20 renders in 1000ms [object Object]

CSP violation (after each crash):

Connecting to 'https://a-api.anthropic.com/v1/m' violates the following
Content Security Policy directive: "connect-src 'self' https://api.segment.io ..."

Steps to Reproduce

Open a new chat in Claude Desktop
Ask Claude to capture an HTML file to Figma using generate_figma_design
Chat crashes with "Failed to load session" before or during the tool call

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1.5749 (ecf3d9) 2026-03-08T18:23:37.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Additional context from Claude Code debug logs (~/.claude/debug/):

The Agent SDK floods the UI with unknown sdk message type: queue-operation and unknown sdk message type: rate_limit_event messages (6,326 and 4,430 occurrences respectively)
plugin:figma:figma-desktop MCP server at 127.0.0.1:3845 always fails to connect — this error repeats on every session start/resume
The generate_figma_design tool call itself completes successfully on the MCP server side (200-2000ms), but the UI crashes when processing the response